Rates of crime have seen truly incredible rates of decline over the past few years. Why has that happened? The Economist examined several theories:

Policing has substantially improved – and people are less likely to engage in crime if they know there’s a chance they’ll be caught.

This is in part thanks to the tools that the police are armed with such as DNA testing, mobile location tracking and surveillance cameras.

Technology has helped in other ways – home burglar systems make it more difficult to rob houses. And since the value of prior luxuries like televisions have dropped, the rewards from successfully robbing a house have also decreased.

Young people are “increasingly sober and well-behaved”. Drug use is less widespread.

Inner cities have been repopulated by a middle class that had earlier migrated to the suburbs.

Since most crime is committed by young people, the general ageing of the western world has led to fewer potential criminals.

Steven Levitt argues that the legalization of abortion reduced the number of children growing up in poverty and who were thus pre-disposed to crime.

Lead exposure might make individuals more likely to commit crime – and so the advent of unleaded petrol might have played a role.

It could just be an anomaly.

The Economist looks at many more explanations…and also why some of the explanations outlined above are extremely unlikely to be true. Read more over here.